On August 11, 2014, Commander-in-chief of the Russian Air Forces, Colonel General Viktor Bondarev claimed that Russia is still continuing the research and development of Su-47 or similar forward-swept wing fighters. The new prototypes of such aircraft will be unveiled in the near future.[3][4][5]

Contents

Originally known as the S-37, Sukhoi redesignated its advanced test aircraft as the Su-47 in 2002. Officially nicknamed Berkut (Golden Eagle), the Su-47 was originally built as Russia's principal testbed for composite materials and sophisticated fly-by-wire control systems.

TsAGI has long been aware of the advantages of forward-swept wings, with research including the development of the Tsibin LL and study of the captured Junkers Ju 287 in the 1940s. Forward-swept wings yield a higher maximum lift coefficient, reduced bending moments, and delayed stall when compared to more traditional wing shapes. At high angles of attack, the wing tips remain unstalled allowing the aircraft to retain aileron control. Conversely, forward sweep geometrically creates increased angle of incidence of the outer wing sections when the wing bends under load. The wings experience higher bending moments, leading to a tendency for the wings to fail structurally at lower speeds than for a straight or aft-swept wing.

The project was launched in 1983 on order from the Soviet Air Force. But when the USSR dissolved, funding was frozen and development continued only through funding by Sukhoi. Like its US counterpart, the Grumman X-29, the Su-47 was primarily a technology demonstrator for future Russian fighters.

The Su-47 is of similar dimensions to previous large Sukhoi fighters, such as the Su-35.To reduce development costs, the Su-47 borrowed the forward fuselage, vertical tails, and landing gear of the Su-27 family. Nonetheless, the aircraft includes an internal weapons bay, and space set aside for an advanced radar.

Though similar in overall concept to the Grumman X-29 research aircraft of the 1980s, the Su-47 is larger and far closer to an actual combat aircraft than its US counterpart.

Like its immediate predecessor, the Su-37, the Su-47 is of tandem-triple layout, with canards ahead of wings and tailplanes. Interestingly, the Su-47 has two tailbooms of unequal length outboard of the exhaust nozzles. The shorter boom, on the left-hand side, houses rear-facing radar, while the longer boom houses a brake parachute.

The Su-47 has extremely high agility at subsonic speeds, enabling the aircraft to alter its angle of attack and its flight path very quickly while retaining maneuverability in supersonic flight. The Su-47 has a maximum speed of Mach 1.6 at high altitudes and a 9g capability.[6]

The swept-forward wing, compared to a swept-back wing of the same area, provides a number of advantages:[6]

The forward-swept midwing gives the Su-47 its unconventional appearance. A substantial part of the lift generated by the forward-swept wing occurs at the inner portion of the wingspan. This inboard lift is not restricted by wingtip stall and the lift-induced wingtip vortex generation is thus reduced. The ailerons—the wing's control surfaces—remain effective at the highest angles of attack, and controllability of the aircraft is retained even in the event of airflow separating from the remainder of the wings' surface.

A downside of such a forward-swept wing design is that it geometrically produces wing twisting as it bends under load, resulting in greater stress on the wing than for a similar straight or aft-swept wing. This requires the wing be designed to twist as it bends—opposite to the geometric twisting. This is done by the use of composites wing skins laid-up to twist. Despite this, the plane was initially limited to Mach 1.6.

As of FY 2013, several engineering modifications have raised the maximum speed parameter limit to Mach 1.8. / Mach 2.2.

As of FY 2014 this new maximum speed limit data is yet to be confirmed by an official confirmation communiqué by Sukhoi.